LOR: Can the Church’s interest in the study of the universe be explained by the fact that astronomy is the only science that has to do with the infinite and therefore with God?What really seems to fascinate both scientists and laymen is whether different physical matter can give rise to life as we know it on earth. Could organisms be silicon-based instead of carbon-based? But one bases this fascination on an implicit erroneous assumption: that matter is the origin of everything, even non-physical things like a soul and intellect of an intelligent life-form. That physical matter is all there is is the materialist's position. But how could an intellect, an intellectual soul, depend on something corruptible like physical matter? It does not because the soul of an intelligent being is one, incorruptible, and immortal (cf. Summa Theologica Iª q. 76 a. 6).
FUNES: To be precise, the universe is not infinite. It is very big, but finite, because it has an age: about 14 billion years, given our most recent findings. And if it has an age, this means that it also has a limit in space. The universe was born in a determined moment and from then is continually expanding.
LOR: But Genesis speaks of the earth, of animals, of man and of woman. Does this exclude the possibility of the existence of other worlds or living beings in the universe?
FUNES: From my judgment this possibility exists. Astronomers hold that the universe was formed by 100 billion galaxies, each of them is composed of 100 billion stars. Many of these, or almost all, could have some planets. How could it not be left out that life developed elsewhere? There is a branch of astronomy, astrobiology, that precisely studies this aspect and has made much progress in recent years. Examining the light spectrums that come from stars and planets, soon it will be possible to single out elements of their atmosphere—the so-called biomakers—and understand if conditions exist for the birth and development of life. For the rest, life forms could exist in theory, even without oxygen or hydrogen.
LOR: Are we referring also to similar beings to us or more evolved ones?
FUNES: It is possible. Until now we have had no proof. But certainly in a universe so big this hypothesis cannot be excluded.
LOR: And this would not be a problem for our faith?
FUNES: I believe no. As a multiplicity of creatures exist on earth, so there could be other beings, also intelligent, created by God. This does not contrast with our faith because we cannot put limits on the creative freedom of God. To say it with Saint Francis, if we consider earthly creatures as “brother” and “sister,” why cannot we also speak of an “extraterrestrial brother?” It would therefore be a part of creation.
—L'Osservatore Romano, the Vatican newspaper
St. Thomas Aquinas took up the question of intelligent extraterrestrials, too:
Aquinas took an interest in the question of whether there were intelligent material beings other than humans in the universe, both as a philosopher and as a theologian. As a philosopher he sought to understand the order of the universe and this entails ascertaining what beings are in the universe. As a theologian he sought knowledge of created beings insofar as it leads to a greater understanding, admiration, and love of the creator, and also insofar as it frees one from superstitious beliefs which pose an obstacle to faith in God. Although Aquinas was unable to approach the question of the existence of intelligent extra-terrestrial life from the scientific perspective of our day, he does raise some generally overlooked philosophical questions regarding the status of such beings. His theological reflections are helpful for addressing the frequently voiced claim that the discovery of intelligent extraterrestrial life would spell the end of Christianity. Aquinas's position is that it is possible that ETs of a certain sort exist, but improbable that they do.Whether there can be non-human life with human-like intellects in the first place is another question.
Aquinas calls to our attention that one sort of ET that could exist is a separated intelligence joined to body as its mover. He himself thinks that there are intelligences of this sort which move the heavenly bodies. As for the other sort of ET which would consist of a separated substance united to a body as its form, Aquinas points that it is extremely unlikely that a pure intelligence be united to a body as its form, since the pure intelligence in no way profits from its union to the body. However, an intellectual substance of the rational sort is suitably united to a body since an intelligence of this sort can only acquire its ideas through sense experience.
Aquinas points out that the sort of body the composite being must have is specified to some extent by the requirements of the intellectual substance that is united to it. The body cannot be a simple body such as air or iron, because sense organs require a balance of elements, and indeed, a most subtle blend of elements; otherwise the being will lack a good sense of touch and well-functioning internal senses that provide reason with the starting points it needs for forming ideas. Aquinas further points out that rational beings need not have fingers, hands, and feet as humans do; he holds that even humans would still be human without them.
Aquinas does not favor the idea that other human-type beings exist because he thinks that the human soul represents the very lowest type of intelligence, whereas the human body represents the very highest material body. However, he does remain open to the possibility.
From a theological standpoint, Aquinas explains that there is no reason for concern here because it is not the task of Scripture to classify the beings in the universe. Since Aquinas does not think that there in fact are other human-type beings, he has little reason to investigate any apparent conflicts between their existence and scriptural statements. His examination of whether many Incarnations are possible is useful for theological discussions of ET existence.
Aquinas explicitly denies that it is probable that other human-type bodies exist, for the reason noted above. There are two other probable arguments that can be drawn from Aquinas, one against and one in favor of the existence of other human-like creatures. On the one hand, the human species would reflect God's goodness in a special way by being unique, while on the other hand, it is befitting to God's goodness that he create more of better creatures. Aquinas leans in the direction of the former view, but realizes that the latter could in fact be the case. And by doing so, he gives us an example of the circumspection that this matter demands.
Having shown that a certain intellectual substance—the human soul—is united to a body as its form, we must now inquire whether any intellectual substance is united to any other body as its form.This definitely goes against a materialist conception of the world and would seem to render true, self-conscious, reasoning artificial intelligence (AI) impossible. Is it?
[I]f an intellectual substance is united as form to one of the simple bodies, it will either be endowed with an intellect only, or will have other powers such as those that belong to the sensitive or to the nutritive part, as in man. In the first case, there would be no point in its being united to a body. For every corporeal form has some operation proper to itself which is exercised through the body; whereas the intellect has no operation pertaining to the body, except by way of moving it; because understanding is not an operation that can be exercised through any bodily organ, and, for the same reason, neither is the act of the will. The movements of the elements, moreover, are derived from natural movers, namely, from generators; the elements do not move themselves. Hence, the mere possession of movement on their part does not imply that they are animated. But, if the intellectual substance, hypothetically united to an element or a part of an element, is endowed with other psychic parts, then, since these parts are parts of certain organs, a diversity of organs will necessarily be found in the body of the element. But this is incompatible with its simplicity. An intellectual substance, therefore, cannot possibly be united as form to an element or to a part thereof.
There is also the fact that the nearer a body is to prime matter, the less noble it is, being more in potentiality and less in complete act. The elements, however, are nearer than mixed bodies to prime matter, since they are the proximate matter of mixed bodies. Hence, the bodies of the elements are less noble in their specific nature than mixed bodies. Since, then, the nobler form belongs to the nobler body, it is impossible that the noblest form, namely, the intellective soul, should be united to bodies of the elements.